When the class starts, there should be a clear list of expectations that each student should be accountable for. Sharing this with your developmentally delayed student should be not be any different than with the other children. He should be held to the same level of accountability, even though he may need more reminding than other students.
A structured environment and scheduled routine will help students with developmental delays anticipate the order of events that occur during school. Have a visual cue such as a clock with the time shown on it paired with a picture of an activity. For example, a swing set could be used to signify recess or a lunch bag to signify lunch. This will help students become accustomed to the school schedule and it will be easy for them to predict what happens next.
The visual cue method can also be used in the classroom by breaking the problem or sentence into steps with pictures showing the events that are occurring. For example, if a math problems states: "Susie has five apples and she gives three away. How many does she have left?", then showing a picture of the apples can help students visualize and process the information more effectively. Using graphs, tables, and other visual media for more complex problems can help as well. For reading, drawing a picture of what is happening can help with reading comprehension and information retention.
If possible, give the student an individual desk so that she can do her work without disturbing the students around her. If this isn't possible, find a classmate who is willing and able to help the student out by holding her accountable for her actions, giving small reminders to focus on the work, and helping her with problems that may be difficult to solve alone. Minimize distractions by placing the student in an area away from places that can take away her attention, such as the door or window. If possible, have her sit close to the front of the class.
When appropriate, encourage the children to interact with one another and allow each student to feel a part of the group. Don't single out your special needs child, but treat him the same as you would another child without special needs. Give your students small tasks and responsibilities such as erasing the board or being the line leader. Make your student feel like an important and valuable part of the classroom.